This invention relates to brake pipe pressure modulating valve devices and more particularly relates to an improved modulation valve device that is simplified by combining application and release propagation signal generating valves coaxially in coaxial stepped bores of a housing.
To minimize time requirement for air brake application and release of a train, it is required that modulating valves be provided, particularly on long railway cars for sensing brake control pressure changes in a brake pipe and locally enhancing the signals for faster propagation of the control signals in a brake pipe of a railway train. This is accomplished at present, for example, by A-1 relay devices having respective accelerating and releasing application valves secured by a pipe bracket at an intermediate point between brake control valve devices. Another such device is disclosed in the U.S. Pat. No. 4,653,812, to Engle granted Mar. 31, 1987, in which several separate valves are required. This patent discloses separate accelerating application and accelerating release valves, but is still much too large and heavy for use on a railway car.
An object of the present invention is to provide improved brake pipe pressure modulating apparatus that substantially obviates one or more of the limitations and disadvantages of the described prior systems. Another object of the present invention is to provide an improved modulating valve device that is much lighter and more compact than the prior art systems.
Another object of the present invention is to provide and improved brake pipe pressure modulating valve device that is simplified and less expensive to manufacture than the above described prior art devices.